Classifier



Jul is, i929.

A. H. STEBBINS CLASSIFIER Filed Oct. 14, 1926 2 Sheets-Sheet 1 ATTORNEY Patented July 16, 1929.

* UNITED STATES" PATENT: OFFICE.

eLAssIrIER.

Application filed October 14, 1926. Serial No. 141,546.

a single air treatment, since the coarse and fine particles tend to cling together, and where the difference in. size of the particles being separated is-slight, complete separation of'the materials can be effected only by subjecting the materials repeatedly to the separating action of comparatively Weak air currents. 4

The present invention therefore relates to a construction in which a group of suction classifiers are supported in a row along the feeding means for the materials being treated so that the materials are repeatedly subjected to the action of the diiferent classifiers.

One of the features of the present invention resides in the construction whereby the larger particles that are separated out of the air in one classifier are returned to the feeding means so that they are subjected to the separating action of the next classifier.

Another feature of the invention resides in the construction of the suction mouths of the classifiers whereby narrow slots are formed in each mouth through which air is drawn into av classifier.

Other features of the invention and novel combination of parts in addition to the above will be hereinafter described in connection with the accompanying drawings which illustrate one good practical form of the invention.

In the drawings Fig. 1 is aside elevation with parts in section of a classifier constructed in accordance with the present invention;

Fig. 2 is a top plan view of the feed table;

Fig. 3 is a vertical sectional view taken transversely through the classifier of Fig. 1; and

Fig. 4 on an enlarged scale is a sectional perspective view through one of the classitiers and the associated feed table.

In carrying out the present invention various means might be employed to feed the materials being treated across the suction mouths of the difi'erent classifiers, and in the construction showna feed table or trough is employed which is supported for vibratory movement so that a progressive vibratory movement may be imparted to the same. It will be apparent however that travel of the materials along the feed table may be promoted by inclining the table in the direction of its length.

The feed table 10 is mounted porting frame consisting of. the uprights 11 to which the side beams 12 are secured and the opposite sides of the frame are connected by the transversely extending braces 13. The feed'table 10 is mounted upon the supporting frame for movement in the direction of its length, and in the construction shown the feed table is provided With the supporting balls or rollers 14 confined between the bearing blocks 15 secured to the frame, and the blocks 16 secured to the under face of the table 10. The means for imparting a progressive vibratory movement to the table or trough 10 to advance the materials along the same might be variously constructed, and in the construction illustrated consists of a pair of operating cables 17 located below the table to extend lengthwise of the upon a supsame and in spaced relation to each other, as

best shown in Fig. 3. Each of the cables 17 has a central portion secured to the under face of the table 10 by clamps '18, and one portion 19 of each cableextends in a lefthand direction from the. clamps 18 about a grooved sheave 20 which is rotatably supported by a shaft 21 that is secured tothe supporting frame. The portion 22 of each of the cables 17 that extends in a right-hand direction from the clamps 18 is looped about a grooved sheave 23 supported by a transversely extending shaft 24 mounted upon the supporting frame. The portion 19 of each of the cables extending from the lower side of a sheave 20 is passed around a grooved sheave 25 that. is rotatably mounted upon an eccentric 26 which eccentric is rigidly secured to the driving shaft 27, and

this driving shaft is rotatably supported by bearing brackets 28 mounted upon the supporting frame. extending from the lower side of the sheave 25 is anchored to the supporting structure by a bolt 29. The portion 22 of the cable extending from the lower side of the sheave 23 is passed around the opposite side of the grooved sheave 25 and extends from the she-ave 2? to a bolt or the like 30 which is yieldingly secured to the supporting structure by the spring 31. Each sheave 25 is The portion of the cable 19 provided with two cable receiving grooves, as will be apparent from Fig. 3, one groove being provided for the cable portion 19, and the other for the cable portion 22. The power shaft 27 may be driven by a pulley 27 to rotate the eccentrics 26 within the1r respective sheaves 25. This will cause .the sheaves to move through o-rbltal path which will serve to alternately tension and slack oil the portions 19 and 22 of the cables 17, to thereby pull the table 10 back and forth. By varying the strength of the springs 31 a progressive movement, which may be as energetic as deslred, Wlll be produced. i Y

The materials to be treated may be fed to the table or trough 10 by the feed hopper 32 having the slidmg gate 33 for controlling the flow of materials. from the feed hopper to the material supporting surface a 34 of the table, and the vibratory movement imparted to the table by the mechanism just described will cause the materials to travel lengthwise of the table in a r1ghthand direction.

The separation of the materials traveling along the table 10 is efi'ected, in accordance wit-h,the presentinvention, by providing any desired number of air classifiers 35 which are arranged in a row along the material advancing table, and each of these classifiers is provided with a suction mouth which is' disposed in close proximity to the material supporting surface 34. Each of the classifiers 35 is constructed to be connected to exhaust means to be described so that air drawn in the classifiers through their suction mouths will serve to pick up the lighter materials traveling along the surface 34, and each classifier is so constructed that the larger particles traveling within the same will be separated out of the air so that these larger particles may be returned tothe material supporting surface 34 for further treatment. 1

In the construction shown each of the classifiers 35 is provided with anlenlar ed head or upper portion in which is'i provi ed v a transversely extending suction pipe 36 and this suction .pipe is disposed at "the central portion of the head so that an inlet air passage 37 is pirovided between the suction pipe 6 and t the .mouth of the' classifier upwardly into the assage 37 and this conduit is oonvenient formed -by roviding the wall 39 .withm each recept'a'c e,'the upper portion of e. inner wall 'of the casing of the classifier. A conduit 38 isv torme within each classifier to conduct air from the inclined wall 40 provided near the lower end of the vertical wall 39 flares outwardly as shown to increase the size of the suction mouth. Each of the classifiers may conveniently be formed of sheet metal and is provided with the side walls 41.

As stated, classification of the materials being treated is effected by exhausting air from the classifiers, and in the construction shown air may be exhausted from each of the classifiers 35 by connecting them to the exhaust pipe 42 which leads to an exhaust fan 43. The pipe 42 preferably increases in diameter in the direction in which the air passes through the same, as shown in Fig. 1, this being desirable to accommodate the increased volume of air supplied to the pipe from the difierent classifiers 35. The suction pipe 36 of each classifieris connected to 'the exhaust conduit .42 by the pipe 44. The classifiers 35 may be supported in 'a row lengthwise of the table 10 with their suction ends in spaced relation to the material supporting surface. 34 by that the larger particles carried into'the classifier by the air will be separated out of the air and returned to the table for further treatment. This is accomplished by providing each of the classifiers with the settling chamber 49 at the lower end of which 'is provided a hopper 50 having a swinging door 51 through which the materials may escape and .fall into the feed trough 10. The suction pipe 36 of each classifier has an opening 52 extending lengthwise thereof through which air may enter such pipe, and it should be noted that this; opening is located adjacent the inner concave face of the curved wall 39, the arrangement being such that a pronounced whirling movement is imparted tothe airpassing through the classifier. This whirling movement serves to throw the heavier particles downwardly within the settling chamber 49 while the lighter particles which remain in the air pass out of I the classifier through the suction pipe 36. The lower end 'of each. classifier is enlarged to cause the same to extend over a larger areaof the deck surface, but'the total area of the air inlet passage 36 should not "be greater at the mouth of the classifier than it is in the upper portion of this passage, since if the area of the mouth of the classifier is too large, the desired suction will not be produced adjacent the material supporting surface. It is therefore desirable to provide a number of spacer blocks or the like 52 within the flaring mouth of each classifier so that the air passages 53 are formed between these blocks, this construction being desirable in order to produce air currents within the passages 53 of sufficient strength to pick up the materials from the surface 34. It may be desirable to regulate the operation of each classifier to cause the same to separate out of the air either larger or smaller particles. This may be done by 1ntroducing air from the atmosphere into the settling chamber 49 and to this end, in the construction shown, the air inlet passages 54 and 55 are provided to introduce air into the chamher 49 through the openings 56 and 57. The amount of air admitted from the atmosphere into the passages 54 and 55 may be a controlled by. adjusting the sliding gates 58 and 59. The material supporting surface 34. is preferably provided with a group of apertures 60 disposed adjacent the lower end of each classifier, and the apertured sections 60 are preferably separated by relatively wide unape'rture sections as shown in the drawings.- As a result of this construction the materials lyin upon the unapertured sections of the sur ace 34 will be subjected to a stratifying action that works the heavier particles down under the lighter particles. This will cause the lighter particles that have been crowded upwardly by the heavier particles to be readily picked up by the air drawn upwardly into the classifiers and as a result the materials traveling along the surface 34 are subjected alternately to. a

stratifying action and suction separation.

From the foregoing description, when read in connection with the drawings, it will be seen that the materials to be treated are caused to travel lengthwise of the table 10 towards the right-hand end thereof so that;

the heaviest particles ass successively across the suction mouths o the various classifiers. The materlals carried .upwardly into each classifier by the air Will be subjected to a separating action within the classifier and, as above pointed out, the heavier particles will be separated out of the air and returned to the table, through the swinging gate 51 of the classifier. In this manner the materials will be subjected time and time again to a separating action as they travel along the table,

After the heavier particles have passed below the suction mouths of a sufficient numher of classifiers, itmay be desirable to revmove such particles from the table 10 and and the fine particles that tend to cling to the slightly larger particles .will be ;removed from the materials being treated.

deck surface and into which the heavier par-- ticlcs may be directed by the inclined deflector plates 62 mounted upon the material supporting surface 34 and constructed so that they will direct the heavier materials to the opposite sides of the table, as will be apparent from Fig. 2. Such materials as may be returned to the table 10 by a classifier adjacent the draw-off spout just mentioned may be directed upon the cover plate 63 mounted above the draw-off means so that these materials will be returned to the table at a point beyond the draw-off means and pass under the suction mouths of additional classifiers for further treatment. The. heavier materials reaching the discharge end of the table may escape into the draw-off spout (ii.

In some cases it may be desirable to force air upwardly,througlr the apertures (30 ofthe material supporting surface 34 to promote separation of the materials. The constrm-tion shown is therefore provided with an air chamber 65 formed below the surface 34 and into which air is forced by a fan 66 the discharge end of which fan is connected to the air chamber 65 by a flexible connection 67. The air forced upwardly through the deck supporting surface 3i will for the most part enter the enlarged suction ends of the classifiers, since the-apertures 60 are provided only adjacent these suction mouths,'but in some cases it may be desirable to provide the table 10 with a cover plate 68 secured to the upstanding walls 69 of the table, and adapted to pre vent air from escaping into the atmosphere. This cover plate is preferabiy provided with holes .to receive the lower ends of the classifier 35, which holes are large enough to permit the table to partake of its vibratory movement without disturbing the classifiers 35 which do'not vibrate. Dust may be prevented from escaping through the openings just mentioned by providing the flexible connections 70 extending from the cover plate 68 to the classifiers, as best shown in Fig. 4.

It may be desirable to vary the strength of the air employed in the different classifiers to cause them to pick up either larger or smaller particles from the table 10. This may be done by providing each connecting pipe 44 with a valve 71 that may beadjusted to vary the amount of air exhausted from a classifier.

' What is claimed is 1'. A machine for classifying materials, comprising in combination, a table having an apertured material sup-porting surface, means for vibrating the table to advance. materials along the apertured surface, air blast means for'forcing air upward through the apertured surface and materials resting thereupon, a cover plate mounted adjacent the table in close proximity to the apertured surface and adapted to confine the air forced upwardly through the apertured surface, a series of air classifiers supported above said cover plate and provided-with suction ends extending downwardly through said plate into close proximity to the apertured surface, and means for exhausting air from said air classifiers to cause themto pick u the lighter materials advanced. by the'table beneath their mouths.

2. A machine for classifying materials, comprising in combination, a table having an apertured material supporting surface, means for vibrating the table to advance materials along the apertured surface, a cover plate mounted upon the table in close proximity to said surface and constructed to form a closed chamber above the apertured surface and to which air is admitted only by passing upwardly through the apertured surface, a series of air classifiers supported above said cover plate and provided with suction ends extending downwardly through said plate into close proximity to the apertured surface, and means for exhausting air from said air classifiers to cause them to pick up the lighter material advanced by the table beneath their mouths.

3. A machine for classifying materials, comprising in combination, a table aving an apertured material supporting surface, means for vibrating the table to advance and means for exhausting air-from the air in close proximity to the apertured surface materials along the apertured surface, a.

tured surface, means forming an air tight flexible closure between the cover plate and each suction pipe extending therethrough,

classifiers. R

4. A' machine for classifying materials,

comprising, in combination, a table having an apertured surface, means for delivering materials to be treated onto said surface for movement along the same, air blast means for forcing air upwardly through the apertured surface and material restin thereupon, a cover plate mounted over the table in close proximity to the apertured surface and adapted to confine the air forced upwardly through the apertured surface, a series of air classifiers supported above said cover plate and provided with suction ends extending downwardly through said plate into close proximity to the apertured surface, means for exhausting air from the air classifiers to cause them to pick up the lighter materials advancing along the apertured surface beneath their mouths, and discharge pipes associated with the classifiers for returning the coarser particles they collect to the table.

"5. A machine for classifying materials, comprising, in combination, a table having an apertured surface, means for delivering materials to be treated onto said surface for movement along the same, air blast means for forcin air upwardly through the apertured surface and material resting thereupon, a cover plate mounted over the table and adapted to confine the air forced upwardly through the apertured surface, a series of air classifiers supported above said cover plate and provided with suction ends extending downwardly through said plate into close proximity to the apertured surface, and means for exhausting air from the air classifiers to cause them to pick up the lighter materials advancing along the apertured surface beneath their mouths.

In testimony whereof I have signed my name to this specification.

ALBERT H. STEBBINS. 

